Re: Status T, A, G, E, Ax, Tx, Ex, I ja HIFI, DIN, DIN NB, Ansi T, SPI
Re: Status T, A, G, E, Ax, Tx, Ex, I ja HIFI, DIN, DIN NB, Ansi T, SPI
- Subject: Re: Status T, A, G, E, Ax, Tx, Ex, I ja HIFI, DIN, DIN NB, Ansi T, SPI
- From: "Markus Hitzler, Color Solutions" <email@hidden>
- Date: Wed, 30 Jul 2003 15:15:47 +0200
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Date: Mon, 28 Jul 2003 09:10:57 +0300
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To: email@hidden
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From: Per Savander <email@hidden>
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Subject: Status T, A, G, E, Ax, Tx, Ex, I ja HIFI, DIN, DIN NB, Ansi T,
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SPI
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I have a customer in a paperlab who wants to be able to use both his
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X-Rite and Gretag instruments for the same measurements, but has a
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challenge in getting the measurements to match eachother.
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What are the specs for the (mathematical) reponse statuses used by
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for example X-Rite (T, A, G, E, Ax, Tx, Ex, I ja HIFI), and how do
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they compare to the responses that Gretag 4.ex. talks about: DIN, DIN
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NB, Ansi T, SPI.
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Anyone?
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Thanks,
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p e r
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--
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Per Savander, PrePress Center Oy, Turunlinnantie 8, 00930 Helsinki FINLAND
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tel: +358 (0)9-34364020 fax: +358 (0)9-3445455 mobile: +358 (0)50-5639200
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Hello Per,
First a short listing about densitometer responses:
Status T / ANSI T: wide band color reflection densitometer response, used
mainly in United States
Status E / DIN: wide band color reflection densitometer response, used
mainly in Europe, main difference to Status T: higher values for yellow
Status A / ANSI A: wide band color reflection and transmission densitometer
response, used mainly in the photographic industry (measurements of prints
and slides)
Status M: wide band color transmission densitometer response, used in the
photographic industry (measurements of negatives)
Status I / SPI, DIN NB: narrow band densitometer responses, rarely used
Status G: "traditional X-Rite graphic arts response", was used about ten
years ago mainly in USA in X-Rite's 400-Series, today only a
"compatiblity-feature" of newer X-Rite densitometers,
=> old stuff
Status Ax, Ex, Tx: Old, classic densitometers use filters made out of glass
(e.g. X-Rite 400-Series) or gelatine (some Gretag instruments). The new
generations of densitometers are spectrally based. This means, that modern
devices measure a spectral curve and use exact mathematical filters to
calculate the density. Contradictory to this the responses of classic
densitometers have slight deviations compared to the responses defined by
ANSI/DIN/ISO, because the accuracy in manufacturing glass or gelatine
filters is limited. X-Rite knows about the differences between the old
400-Series and the new spectrally based 500-Series. For users, which have to
use both series they provide the Ax/Ex/Tx response to get density values out
of a 500-Series instrument, which correspond with the densities of the 400
Series.
=> also old stuff, if you don't have to use a X-Rite 400
HIFI: Status E responses for CMYK, additional filters for red, green, blue
and orange)
The mainly used responses are Status A, Status E and Status T.
Related standards are: ANSI PH2.18, DIN 16536
If you want to compare density measurements of different instruments a
further main component is of course the polarization filter. Slight
differences between two manufacturers are unfortunately "normal", even if
you choose the same status in the densitometer setups.
Some words about densities:
Pressroom:
Densities are very useful, when you want to control the amount of ink on the
paper of a very well known printing process in a very easy way. Here we're
talking about relative process control.
If you want to set up a printing process to an industry standard, you need
of course a spectrophotometer, because there are lot's of color differences,
which a densitometer can't "see".
So normally we're doing the setup (for standardized printing) with a
spectro, using L*a*b* values, and control the constancy and equability of
the printing process after the setup mainly through densities (because
process control through densities is easier to the printer). The intended
densities for this are determined at the setup of the machine. This means,
that the densities here are only used as relative process values. Because of
this it doesn't matter, which response you use, if you do your setup and
quality control with L*a*b* values.
Proof:
At proof systems the situation is "slightly" different:
Most RIPs, which are used for proofing are delivered with predefined
ICC-Profiles for different printer/ink/paper-combinations. This ICC-profiles
are based on the linearisation of the printer. The operator normally uses
the ICC-profile which's delivered with the RIP and does the linearisation by
himself to keep the proof system stable. Here it is very important, that the
densitometers/spectrodensitometers, which are used for the linearisation
measure exactly the same density values.
Because of this we're calculating all densities in our measurement software
basICColor catch based on the spectral curves we get from the
spectrophotometer. This eliminates errors through different density
calculations inside the measurement instrument.
BasICColor catch connects to nearly every spectrophotometer on the market,
calculates density values (Status A, Status E and Status T based on the
ISO/ANSI/DIN standards) and CIEXYZ/CIELAB (different illuminants possible)
and has an automatic report function with an easy pass/fail judgment (like a
traffic light).
Regards,
Markus
___________________________________________
Color Solutions Cologne
Markus Hitzler
August-von-Willich-Str. 155
50827 Kvln
Telefon: +49 (0)221 99 175 80
Fax: +49 (0)221 99 175 81
Mobil: +49 (0)171 8390333
Email: email@hidden
Web:
http://www.basICColor.de
___________________________________________
basICColor - the basICCs of colormanagement
___________________________________________
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